The present invention relates to animal litters, and in particular to clumping animal litters based on organic materials.
Various clays (primarily bentonite) have been used as a base material for absorbent animal litters for some time. These materials become tacky when wetted, thereby forming a “clump” that is easily removed when cleaning a litter box. Many animals, cats in particular, will often refuse to use a litter box that is not kept scrupulously clean. Clumping animal litters facilitate ease of cleaning since otherwise the litter box must be periodically dumped and refilled to maintain appropriate cleanliness.
An important disadvantage of clay-based litters is that they aggressively stick to the sides and bottom of the litter pan when wetted. This tendency makes removal of the clumped litter more difficult, partially defeating the purpose of the clumping action. Litter stuck to the sides and bottom of the litter pan also requires more frequent replacement of the litter box itself, since the animal urine odor will be imparted to the plastic or other porous or semi-porous material from which the litter box is formed. It would thus be desirable to develop a litter material that results in “softer” clumps, that is, clumps that stick together sufficiently for removal from the litter pan but that do not stick as easily to the sides and bottom of the litter pan.
It has been recognized that a litter based on organic materials rather than clays would be highly desirable. Organic materials, such as sawdust and lumber mill scraps, are readily available and inexpensive. They are more absorbent than clay materials, and naturally contain chemicals that will control odor. Organic materials may be formed into pelletized shapes using a pellet mill; such mills have long been used in the manufacture of animal feed. A significant drawback of organic materials, however, is that litters based on organic materials have historically lacked the highly desirable clumping feature of clay litters. Attempts to develop clumping organic litters have been unsuccessful due to the techniques of production attempted, and the high cost of the various ingredients used to create the clumping action in an organic-based litter.
The related art includes a number of attempts to develop cellulosic materials in the manufacture of animal litter, and in particular the use of wood particles. For example, U.S. Pat. No. 3,941,090 to Fry teaches a cedar-based animal litter with an alfalfa binding agent. U.S. Pat. No. 4,258,659 to Rowell teaches a cat litter comprising soft wood particles formed from waste wood material, including sawdust and wood pieces, collected from sawmills. U.S. Pat. No. 5,044,324 to Morgan et al. teaches the manufacture of wood fiber “crumbles” that may be used as animal litter; the crumbles are formed from the grinding of pelletized wood fiber. U.S. Pat. No. 5,271,355 teaches the combination of ground wood chips and peat to form animal litter.
The related art also includes a class of improved clay-based clumpable litters, that is, litters that have an especially strong tendency to agglomerate in the presence of moisture. These litters materials are generally composed of a substrate material to which a coating is applied; the coating portion of the material provides the clumping action. For example, U.S. Pat. No. 5,014,650 to Sowle et al. teaches an animal litter with a porous, inert solid substrate, such as clay, and a coating composed of a water-absorbent polymer. U.S. Pat. No. 5,339,769 to Toth et al. teaches a method of forming such a litter in which a liquid clumping agent is distributed over a dry blend of materials that may include an inert solid substrate and a clumping agent.
This pellet coating technology has also been applied to litters based on organic materials; for example, U.S. Pat. No. 5,970,916 to Yoder et al. teaches a litter material composed of a cellulosic substrate with a first layer of xanthan gum and a second layer of guar gum. Also, U.S. Patent Application Publication No. 2002/0038633 to Hayakawa teaches a cellulose ether as a binder that is responsible for a clumping action in a litter composed partially of organic material. As noted in Hayakawa, however, the use of cellulose ether increases the manufacturing cost of the product, and the goal of Hayakawa was to develop a product that required the use of cellulose ether in smaller quantities. Hayakawa teaches that this is achieved through the selection of high molecular weight—that is, high viscosity—cellulose ethers. The base material or substrate taught by Hayakawa includes inorganic minerals, such as bentonite clays, as well as organic materials.
The use of various gums, including guar gum, and carboxymethylcellulose (CMC) are known in the manufacture of animal litters, and in particular in the manufacture of animal litters that contain organic materials. U.S. Pat. No. 5,664,523 to Ochi et al. teaches a base litter material that includes both organic and inorganic components, but also includes 15–55% guar gum by weight. U.S. Pat. No. 6,053,125 to Kory et al. teaches a clumpable cat litter formed of corncob grit and components that are coated with guar gum. U.S. Pat. No. 6,089,189 to Goss et al. teaches a cellulose-based litter product wherein cellulosic granules are treated with an adhesive and mixed with a particulate polymeric clumping agent, preferably guar or locust bean gum.
A significant drawback of all known animal litters with clumping action is that they are not readily flushable. To the inventor's knowledge, all of those commercially available litters that are advertised as flushable, including both clay-based and grain-based litters, also require a soaking period before flushing, typically ten minutes or so. None of these products allow the pet owner to simply scoop the clumped litter from the box, dispose of the clump in the toilet, and flush immediately without substantial risk of a clog or damage to plumbing. This is a significant inconvenience, since the pet owner must remember to return at a later time in order to flush the material. Failure to allow sufficient soaking time with these litters may result in clogged plumbing.
The inventor's experiments have determined that none of the available and tested litter products are fully successful in combining the advantages of an organic litter material with the clumping action of a clay litter, to result in a product that may be manufactured at a competitive cost. The inventor has recognized that an ideal clumping litter would eliminate the use of clay or other inorganic base materials, and would maximize the quantity of inexpensive organic materials with respect to any required additives. The limitations of the related art as described herein are overcome by the present invention as described below.